It's early on a Monday morning on the Hollywood sets of CBS' new medical drama "Three Rivers," which premieres Sunday, Oct. 4, and star Alex O'Loughlin, wearing only scrub pants and a striped bathrobe, is sprawled across a hotel bed.

Suddenly there's a burst of rock music, sending O'Loughlin ("Whiteout, " Moonlight"), who plays transplant surgeon Dr. Andy Yablonski, stumbling into the next room. There he discovers a patient playing the video game "Rock Band." By the end of the scene, the two are happily jamming.

Between takes, O'Loughlin shows off his air-guitar skills with the game, then picks up a real acoustic guitar and makes some music.

"I was just mucking around," he says. "It's a beautiful guitar they've got in there. It's a vintage Gibson. It's divine. It's worth a lot of money, so I'm hesitant to pick it up. But it's its karma. It's supposed to be played."

If this scene doesn't sound like the usual medical drama, that's the goal of series creator and executive producer Carol Barbee ("Jericho," "Judging Amy," "Providence").

"I know we're doing a medical drama," she says, "but it doesn't feel like that. It feels like we're doing these stories about these lives. The guest-star stories are so interesting, because you're dropping into these worlds.

"It's the worst day; something catastrophic happens. You don't know that you're going to be a donor that day."

Set at a hospital in Pittsburgh (the city is at the confluence of three rivers, hence the show's name), the drama focuses on the organ-transplant team. Led by Yablonski, it also includes rebellious but talented Dr. Miranda Foster (Katherine Moennig), womanizing Dr. David Lee (Daniel Henney), operating assistant Pam Acosta (Justina Machado) and transplant coordinator Ryan Abbott (Christopher J. Hanke), who gave up journalism to help the team with the complex logistics of pairing donated organs and transplant patients.

Overseeing the team is head of surgery Dr. Sophia Jordon ( Alfre Woodard).

Of course, since "Three Rivers" is about transplants, there has to be a donor, which means someone has to die so someone else may live. But that doesn't mean the show or the characters have to be earnest and grim all the time.

"The stakes are always there," O'Loughlin says, "and these are people that deal with this on a day-to-day basis. They live in the light. These are some of the funniest, most joyful people that I've ever met, because that's the only way you can deal with death on this scale every minute, every hour of every day.

"So that brings us in. Then there's this team that gives life. That's what they do as a team at Three Rivers. They give hope; they give life. They're in the life business."